US2381992A

US2381992A - Control system

Info

Publication number: US2381992A
Application number: US453827A
Authority: US
Inventors: Joseph P Vollrath
Original assignee: Brown Instr Co
Current assignee: Brown Instruments Co
Priority date: 1942-08-06
Filing date: 1942-08-06
Publication date: 1945-08-14
Anticipated expiration: 1962-08-14

Description

Aug; 14, 1945.

. INVENToR. JOSEPH PMOLLRATH Aug. 14, 1945. .1.A P. voLLRATH CONTROL. SYSTEM 2 sheets-Sheet 2 Filed Aug. 6, 1942 INVENTOR. FIG. 3. JOSEPH P.VOL\ RATH www? ATTO NFY i Patented Aug. 14, 1945 u wfnormalf Topreyentsuciri Occurrence, operc0821 passes through.- he mulini 's into a l ation of thefuelfsupply m @muy kim in such is prcvided on Vitssurfacewith tracks I that are lljwhich is gervee as a measured pressure.

nects the control apparatus at times when the temperature of the kiln is being measured.

The coal feed motor-I4k is. controlled in response to an over supplyor an under supply of coal fed from the pulverizer II. To this end there is provided a pressure controller 24 which is responsive to the pressure in the coal line, and i is connected thereto by means of a pressure line 25 and a lter 26. 'If for some reason, the coal g has become jammed in the'pulverizer, and is not pipe I6, above which the lter is located, will drop due to the action of the'injecti'on air in pipe I1. If, however, the burner I8 should become clogged, coal would continue to be fed through the pipe I6 and the pressure would rise. This control instrument may be a controller such'as is disclosed in Side Patent 1,969,158, issued August '1, 1934,v

i v15 going properly to the furnace, the pressure 1n the i which patent discloses thecontrolling of switches l in response to the increase and/or decrease of the motor, an alarm 28 may be connected in the the coal feed motor is not operating properly.

The iilter, as is shown best in Figure 2, consists of a plurality of conical

shaped expansion chambers

30 and 3l and 32 which are placed one Y ,tween them serve to stop any coal dust that.

might otherwise clog the line 25 and render the controller 24 inoperative. There is also shown in i In addition to controlling tiometer instrument 23. The arrangement is such that when the temperature deviates a slight amount from some normal value, switches HI or LI will be rclosed depending upon whether the temperature is high or low. When the temperature deviates a large amount from the normal value, switch H2 or L2 will be closed. These switches control the energization of the coils of relays RI, R2, R3, and R4. Each of the relays controls two switches. When the switch H2 is closed in the instrument, coil Rl will be energized to close switch RII and form a holding circuit for the coil and to close switch RI2. switch HI is closed, coil R2 will be energized to A dose switches Rzl and R22. when switch Ll is closedyrelay R3 will be energized to close switches R3Iy and R32 and when switch L2 is closed, relay R4 will be energized to close switches RM and R42. Even thoughy the potentiometer switches may be closed, the relays cannot be energized unless aselctor switch 46 is also closed.v

The fvariable speed mechanism I5 has its speed V Y adjusted by a reversible electric motor 41, the

` circuit so that-an attendant will be'notifled when i The size of these chambers this figure a grease cup34 which serves to lubricate the bearing atrthe end of the screw feed. It is notedthat the controller 24 'is provided with a pen35V that will make a record of the pressure and, therefore, the operation of the coal feed motor, on aA chart 36. The controller 24, ras above .y

noted, serves to stop the motor I4 when the presl sure in thercoal feed line reaches a predetermined maximum or minimum value, and serves to opg .erate the signal 28 whenever the motor stops.

This controller also operates a switch which controls thestarting and stopping of a timer 21 that serves a purpose to be later described.

Referring next to the wiringr diagram of Figure 3, it will vbe vseen that current is supplied to the control system through lines LI and L2 that .are y provided withv a main line switch 31. The signal 28 is'conne'cted across the lines in circuitwith a V 21 is connected across the line in series with the 'switch 4I.

The switches 37B, 39v and 4I are the switches operated by the controller24.Y

fields of which can be energized in several ways. Field 54 of the motor 41.15 connected at one side directly to the line and at the other side t'hrough limit switch 4,8, manual switch and either switch RIZ and interrupter 'switch 53, or switch R22 and interrupter switch 52. Theeld 55 is connected across the line through limit 'switch 49, manual switch5| and either switch R32 and interrupter 52 or switch R42 and interrupter 53. The interrupter 52 isa switch. which is `opened ,and closed in .synchronism with the speed of the kiln and is preferably driven lin some 'manner from the kiln,-as is shown diagrammatically in Figure 4. In that figure there are shown a plurality of projections 6I extending from thesurface of the kiln that are adapted to engage one endA of arpivoted'support 62 for theswitch 52. The projections move the Support around its pivot against the bias of a spring VI3to close the switch. A suitabl stop 64 determines the normal l Y `'position of the support 6 2, in which the switch 52 isopen. lThe switch.- 53 is an interrupter switch whiclis opened and closed at periodic linteryals which are generally longer than the intervals that switch 52 is closed and may be of the type shown in Moore Patent 2,235,560, granted March 18, 1944. 'It `will be seen that if the temperature has deviated only a slight amount from normal, switch R22 or R32 will be closed to energize-.one ofthe fieldsfof. the motor for pel, riods of time depending upon the operation of the The timer may be vof any conventional type l but is shown here as consistingV of a coil 42 which i serves toheat a bimetallic strip 43 that, when heated, will warp tothe left to bring contact 44 into engagement with contact 45. The speed with which the contacts close 'after currentis supplied to the coil 43 will dependV upon the amount of heating resistance in the coil. This may be adjustable to vary the timing of the switch.

The timer switch controls the supply current to the control switches which Voperate the variable speed mechanism. The primary switches of the control system consist of switches HI and H2 and LI and L2 that are operated by the poteninterrupter switch-52. ture has deviated a large amount from normal either switch RI 2 or R42 will be closedto energize the motor for periods of time depending upon the operation of switchf53. Y In any event, the motor may be operated in either direction by the closure of manual switchesV 50 and 5I. In the motor control circuit, there is also provided a switch 56. This `switch when it is in the position shown permits automatic control ofthe motor 41 through the controlcircuit just. described. When aswitch 56 is opened by pressing the' upper button, the automatic controll system will be disconnected and the motor 41 can only b e operated upon the depression lof switches 50 and.5I.

Whilerthe operationof the system should be obvious from the above' description, a short sum- If, however, the temperamaryV will now be given. Assuming that the kiln is operating in a normal fashion, the motor4| will bedriven in one direction or the other for periods of time depending upon Vthe deviation `of the temperature from normal at such times that the switch 46 is closed indicating that-thetemperature of the kiln is being measured. If the temperature of the kiln is high', either relay Rl or R2 will be closed so that the.` motor 54 will be driven for periods of time depending upon the amount of deviation to slow down the supply of fuel; If the temperature of the kiln is low, either relay R3 or R4 will be closed to energize the field 55 for periods of time depending upon the amount of deviation to speed up .the supply of. fuel.

If during the operation of the system, the supply of coal should either run out or the burner I8 should become clogged, the controller 24 will operate to open switch 39 to stop the motor I4 and close switch 38 to start the alarm operating.

The ,controller 24 will also open switch 4| to de-energize the timer coil 42 and permit contacts 44 and `4 5 to be separated to prevent any subsequent operation of the speed changing motor 4l. When the cause for the distirbance to the supply of fuel has been located, and corrected, the motor I4 may'again be started. The controller 24 at this time closes the switch 4l, and a predetermined time later, the coil 42 will be heated suiciently to cause contact 44 to engage contact 45. At this time, the control system will again operate. The purpose of the delay in operation of the control system after the supply of fuel has been started is to permit the kiln to be fired for a long enough period of time so that its temperature may stabilize before the fuel supply is changed. The fuel supply, at this time will probably be very close to that necessary, since the speed change mechanism has the same setting that it had when the system was stopped.

From the above, it will be seen that I have provided a control system yfor rotary kiln which will adjust the fuel supply in accordance with deviations of the temperature from a normal value and will make a record of the speed of the kiln. It will also be seen that the control system is provided with a means to delay its operation until a predetermined time after the system has been started up, so that the control system can be quickly stabilized. The system also provides the means responsive to the supply of fuel to control the entire operation of the control system.

While in accordance with the provisions of the statutes, I have illustrated and described the best form" of embodiment of my invention now known to mefit will be apparent to those skilled in the art that changesmay be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and that in some cases certain features of my' invention may be' used to advantage without a corresponding use of other features.

Having now described my invention, what Il claim as new and desire to secure by Letters Pat'- ent is: Y

1. In a kiln control system, thecombination of `means to supply fuel to said kiln, `means responsive to a condition of the supply of fuel to th'e kiln to stop and start said fuel supply means as said condition varies'froma normal value, means to measure the temperature of the kiln, mechanism operated by saidlmeasuring` 'means to vary the speed of said fuel supply means in accordance ing means to regulate said adjusting means in response to temperature variations of the kiln to maintain the temperature of the kiln substantially constant, means responsive to the supply of fuel to stop said drive means when the fuel pressure fallsbelow or increases above predetermined limits, and timing means to delay operation of said mechanism for a predetermined period of time after'said drive means has started whereby kiln conditions may become substantially stabilized before the fuel supply is varied.

3. In a kiln control system, the combination of means to measure the temperature of the kiln, variable speed means to supply fuel to said kiln, means operated, by said measuring means to speed up said variable speed means in response to a reduction in temperature of the kiln and to slow.

down s'aid variable speed means in response to an increase in temperature of the kiln, and means operative to delay operation vof said means operated by said measuring means for a predetermined pericd of time each time said variable speed means is started whereby kiln conditions lmay become substantially stabilized before the kiln, a first interrupter-driven at a speed propor-v tional to the speed of rotation of the kiln, a second interrupter driven at a constant speed with a periodof operation longer than that of said first 'interrupten means operated` by said measuringY means to adjust said variable speed means for periods 0f time limited by said first interruptor if the temperature is a relatively small amount from normal and to adjust said variable speed means for periods of .time limited by said second -interruptor if the temperature of the kiln is a relatively large amount from normal, and means to delay the operation of said variable speed means a predetermined period of time each time A the control system is started after a shut down whereby kiln conditions may become substantially stabilized before the fuel supply is varied.

' 5. In a kiln control system, the combination of means to measure the"temperature of -a kiln, means to supply fuel to said kiln, drive means for said supply means, means operated by Said'measuring means Yto adjust said drive means and vary the supply of fuel in accordance with the temperature' of the kiln, means responsive to theY pressure of the fuel supplied to the kiln to stop and start the drive means, and mechanism oper- `ated by said responsive 'means to delay the operation of adjusting said drive means for a predetei'-,` mined time after said drive means has started up whereby kiln conditions may become substantially interposed between said drive'means'A and said supply meas;meansl respoxisiveftq the pressure of the fuel in,V the supply means to'control lthe opeatio'n of the drive meax'is, means vresponsive to the temperature oi the'kiln to c'ontrol the operai' tion of said variable speed mechanism, and 'meaiisV Qf-the'fuel'te delay the starting 'f said variable speed `mechanismfu'ntil a pi'edetermined time after said drivehmea'n's `has; started whereby kiln vconditions may jbeome substantial'ly; stabilized